Carglumic acid: an additional therapy in the treatment of organic acidurias with hyperammonemia?

Hyperammonemia in patients with methylmalonic aciduria (MMA) and propionic aciduria (PA) is caused by accumulation of propionyl-CoA which decreases the synthesis of N-acetyl-glutamate, the natural activator of carbamyl phosphate synthetase 1. A treatment approach with carglumic acid, the structural analogue of N-acetyl-glutamate, has been proposed to decrease high ammonia levels encountered in MMA and PA crises. We described two patients (one with MMA and one with PA) with hyperammonemia at diagnosis. Carglumic acid, when associated with standard treatment of organic acidurias, may be helpful in normalizing the ammonia level. Even though the usual treatment which decreases toxic metabolites remains the standard, carglumic acid could be helpful in lowering plasma ammonia levels over 400 micromol/L more rapidly.